Method of refining hydrocarbons



Jan. 25,1927.

O. D. LUCAS ET AL- METHOD oF REFINING HYDROCARBOS Filed April 50, 1924 Patented Jan. z5, 1927.

UNITED STATES PATENT OFFICE.

OWEN DAVID LUCAS .AND ERNEST LAWSON LOMAX, 0F WESTMINSTER, ENGLAND,

.ASSIGNORS TO V. L. OIL PROCESSES LIMITED,

BRITISH COMPANY.

OF WESTMINSTER, ENGLAND, A

METHOD 0F REFINING HYDROCARBONS.

Application led .April 30, 1924, Serial No. 710,144, and in Great Britain November 14, 1923.

This invention relates to the rening of hydrocarbons in the vaporized state, more especially hydrocarbons of the lighter type, the chief object being to retain in the refined oil ingredients which may be safely left in, in the case, for example, of motor fuel,

but are removed by the usual treatment.

The usual method of refining hydrocarbons is to wash the crude distillate With strong sulphuric acid and then with alkali, the acid removing objectionable constituents which spoil the colour of the finished product and have polymerizing tendencies, At the same time the acid removes certain unsaturated constituents which, from the point'of view of a motor fuel, may be safely and even with advantage left in. The loss from such refining operations may amount to from'25 to 28 per centi-0f the bulk treated.

According -to this invention the distillate from the crude hydrocarbon (after subjection in most cases to weak acid and alkali treatment), is heated, under a pressure which prevents Vaporization, to a' temperature above the normal boiling point of its highest boiling point constituent and is then allowed to expand as a vapour into a heated filtering chamber containing a polymerizing agent which effects polymerization and separation out from the vapour of undesirable constituents If the hydrocarbons have been produced by the distillation of coal, lignite or the like and may therefore contain phenols and bases, the preliminary treatment by chamber acid (which is Weak compared to Athe acid employed in the customary treatment) and alkali is necessary.

The distillation may be carried `out at a temperature of from 180 to 200 C. at a pressure of about 130 to 150 lbs. per square inch. Or the heat may be applied in two' stages, say, a preliminary heating to about 100 C. under a pressure preventing vaporization, of the order of 20 to 30 lbs. per square inch. and the heating in the filtering or polymerizing chamber through a heat jacket would be carried to the higher temperature required. Or distillation may be in two or more stages, giving two or more fractions according to the range of boiling points required in the final products, say, two fractions up to 130 C. and from 130 t0 200 C. respectively. The fractions are then treated separately.

The accompanying diagram shows the general arrangement of a plant suitable for carrying out this invention, the individual i the pump B. C is a furnace heating the pipe still D from which the highly heated oils pass under the required pressure to the expansion valve E. The suddenly produced vapours pass through the pipe f into the vapour filter F supplied with the polymerizing agent f above the perforated bottom plate f2 below7 which the end of the tube f opens so that the vapours pass through the complete body of material ff before they escape to the condenser G from the upper end of the filter F. From the condenser G the light purified spirits pass to the storage tank H. Inert gas enters at f?.

The amounts of acid and alkali used in the preliminary treatment depend upon the particular character of the hydrocarbon. but would amount approximately to 2 per cent of per cent acid (chamber acid) and 5 per cent caustic soda solution of 10 per cent strength and calculated by weight of distillate. The strength of acid and the amount used are both considerably lower than in the usual treatment. The equivalent quantity of sulphuric acid in more concentrated form would be detrimental. The object `of this preliminary treatment is bases and acids, such as phenols, and the amount of acid and alkali employed should be in proportion Ato the quanity of such ingredients present The useful unsaturated constituents removed by strong acid are not eliminated. The heating of the washed hydrocarbon is carried to a temperature of about 10 to 20 above the highest boiling point of the constituents and the filtering chamber may be provided with lioridin, bauxite, activated carbon or other suitable purifying agent preferably in' granulated form, the chamber being kept at a temperature which will prevent condensation of the vapour passing from the chamber to condensers of usual type At the point of expansion into the filtering chamber a carrying gas is introduced, such as hydrogen or carbon dioxide, chemically inert as regards the oil vapours and preferably heated to ,prevent risk of condens- Y merized bodies in the vapour, so that the polymerized bodies are substantially eliminated from the vapour. But forI the gas carrier complete separation of these bodies would be diicult. The inert gas is returned to the system after condensation of the vapours, losses being made up as required. It is found that there is obtained by this treatment a. permanent Water White spirit free from objectionable odour, while the loss on treatment'may be reduced to below 10 per cent, this varying, of course, with the nature and quality of the crude hydrocarbon.

The following is an example of the process. The distillate from crude benzol, after distillation to about 180 C. is treated with about 2 per cent of chamber acid and then with about 5 per cent of a. 10 per cent solution of caustic soda. On heating the treated material, after settling, to a. temperature of about 200 C. under pressure vof 150 lbs. per square inch, it is allowed to expand into thc filtering and polymerizing chamber, maintained at about 200 C. with about 3 to 5 cubic feet of carbon dioxide per gallon of the spirit treated, the vapour being then drawn olf and condensed in separate apparatus. i

What We claim and desire to secure by Letters Patent of the United States is 1. A proce for the refining of light hydrocarbons, which consists in heating the hydrocarbons under a pressurex which prevents vaporization to a temperature above the normal boiling point of its highest boiling point constituent and then expanding the hydrocarbon suddenly as a vapor into a heated filtering chamber, causing it to come into contact with a polymerizing solid absorbent in the said chamber and separating out the polymerized bodies from the hydrocarbon vapor.

2. In a process as claimed in claim 1, adding to the hydrocarbon vapor as it expands into the filtering chamber a small proportion of a permanent inert gas which mingles With the vapor and passes With` it into contact with the polymerizing agent.

3. A process for the refining of light hydrocarbons containing phenols and other objectionable ingredients which consists' in washing the light impure hydrocarbon with a small percentage of dilute acid and subsequently n-'ashing with alkali solution so as to remove free bases and acids without *eliminating unsaturated hydrocarbons, heatvapor into a heated filtering chamber, caus-V ing it to come into contact witha polymerizng solid absorbent in the said chamber and separating out the polymerized bodies from the hydrocarbon vapor.

OWEN DAVD LUCAS. ERNEST LAWSON LOMA/iX. 

